Jazz, Popular Music & the Recording Age: How the Last Hundred Years Sound

Most pop songs in the world use the same five or six moves. A bass player leans on the first beat, a snare lands on the second and fourth, a singer sets a hook above three or four chords. Yet a 1950s blues, a 1960s Motown single, a Kingston dub and a Seoul pop release do not sound alike. What changed was not the alphabet but how it was played, and, from the 1920s on, how it was captured: the studio stopped recording music and became part of it.

This piece follows that thread from the blues through jazz to hip-hop, reggaeton, Afrobeats and K-pop, with the players and engineers who made the sounds and the courtrooms that argued over who owns them. Modern songs are described here in words and chord numbers only; no lyrics, and no melodies from songs still under copyright.

This is about how music is made and the law that surrounds it; it is not legal advice. Listening loudly for long enough damages hearing; keep the volume where you can still talk over it.

The blues: twelve bars that hold a century

The blues grew in African American communities of the American South around the turn of the twentieth century and was first widely recorded in the 1920s: Mamie Smith and Her Jazz Hounds recorded "Crazy Blues" for Okeh on 10 August 1920, and it sold about 75,000 copies in its first two months, opening a market for recordings by Black artists. Its form is the twelve-bar blues: three lines of four bars. In Roman numerals (I is the chord on the key note, IV a fourth above, V a fifth above) the usual version is I I I I, IV IV I I, V IV I I, with the last bar often turned around into a V to pull the form back to the start. Each chord is usually a dominant seventh (I7, IV7, V7), whose flatted seventh is itself part of the blues colour; singers and guitarists also bend the third (and sometimes the fifth) between its minor and major forms, notes that have no key on a piano. The words usually follow an AAB shape (a line, the same line, an answer), which is call and response again.

The form's genius is its economy. Because everyone knows where the bars are, a band can start with no rehearsal, and the soloist has room to say something new each chorus.

Swing: a long-short you can't write down

Notation writes two eighth notes as equal. Jazz players play them unequally: the first is longer than the second, in a ratio that depends on tempo, style and player. A "triplet feel" is 2:1, so the long note is two thirds of the beat. Measurements of ride-cymbal playing on classic jazz records (Friberg and Sundström, 2002) found a ratio close to 3.5:1 at slow tempos that gradually closed toward 1:1 at fast tempos, which is why a fast bebop line doesn't sound like a slow blues at the same ratio. Drummers tend to use bigger ratios than horn soloists. In other words, swing is not a rule but a proportion that musicians adjust to the music.

Jazz harmony: ii-V-I and the guide tones

Jazz grew out of New Orleans brass bands, ragtime and blues in the early twentieth century, passed through the dance-band swing of the 1930s and the faster, harmonically denser bebop of the 1940s, and kept branching. One chord move runs through nearly all of it: the ii-V-I, a minor seventh chord on the second degree, a dominant seventh a fifth above the next, and a major seventh home. In C that is Dm7, G7, Cmaj7. The move works because of two voices inside the chords, the guide tones: the third and the seventh. Between these chords they move by a semitone or not at all, so the harmony turns a corner while two notes barely move.

Players use that to choose notes in a solo: arrive on the third of each new chord. And a tritone substitution swaps the V7 for the dominant seventh a tritone away (D♭7 for G7): the two chords share the same third and seventh with their roles swapped, so the smooth line survives and the bass line moves down by semitone. Miles Davis's Kind of Blue (recorded 2 March and 22 April 1959, released 17 August 1959) took the opposite route to the same freedom: modal jazz, where a player gets a scale for long stretches instead of quickly changing chords. Both are still in use.

Backbeat, break and dembow: the drum patterns of popular music

The backbeat is the snare on beats 2 and 4, which turns a pulse into a push. It came from rhythm and blues and rock and roll and is the spine of funk, soul and rock. Funk shifts the emphasis onto the downbeat and the small subdivisions around it: in "Funky Drummer", recorded by James Brown on 20 November 1969 and released in 1970, drummer Clyde Stubblefield's improvised break became one of the most sampled recordings in music. Disco put a kick on all four beats with open hi-hats on the offbeats; house music kept it.

Hip-hop began at a back-to-school party at 1520 Sedgwick Avenue in the Bronx, dated 11 August 1973 (a date heavily marketed since), where DJ Kool Herc extended the instrumental "break" by cutting between two copies of a record. Rap, break-dancing and DJing followed, and "Rapper's Delight" by the Sugarhill Gang (1979) took it to a wider audience. In 1980 Roland released the TR-808, an analog drum machine of synthesised drums with a step sequencer, which cost US$1,195 and sold poorly, but by 1983 used units went for under $100 and its sounds became a signature of hip-hop and dance music, as on Afrika Bambaataa and the Soulsonic Force's "Planet Rock" (1982). Hi-hat rolls over a half-time snare mark later trap.

One groove, many ports: reggaeton, Afrobeats and K-pop

The dembow rhythm takes its name from Shabba Ranks's "Dem Bow" (1990), which rode a Jamaican riddim made by Steely and Clevie in 1989; it is a boom-ch-boom-chick pattern built on the 3+3+2 grouping that Latin American music knows as the tresillo. Puerto Rican artists from the early 1990s sampled and re-recorded versions of it, and the genre that grew from that, reggaeton, is built on it. Hear it in the box: kick on every beat, the snare hits falling on the fourth and seventh sixteenth of each half-bar, a 3+3+2 count.

Afrobeat (no s) was created by Fela Kuti in 1960s and 1970s Nigeria from highlife, jazz and funk: big bands, long grooves and political commentary. Afrobeats (with an s) is a different, newer umbrella term for West African pop of the 2000s and 2010s, blending highlife, hip-hop, dancehall, R&B and other styles; the "s" is credited to the London DJ Abrantee Boateng, around 2011. It is mostly in 4/4, often with a 3-2 or 2-3 clave underneath (try the C track). Wizkid's "One Dance" (with Drake and Kyla, 2016) became Spotify's most-streamed song at the time.

K-pop dates its modern form to Seo Taiji and Boys, who debuted on 11 April 1992 with a hip-hop, techno and rock fusion; SM Entertainment (founded by Lee Soo-man in 1995) built the training-and-debut "idol" system on the model of Japan's, with trainee periods of at least a year and up to six, and no guarantee of debut. The term "K-pop" first appeared in Billboard on 9 October 1999. Its songs draw on pop, rock, hip-hop, R&B and electronic styles, and foreign writers and producers increasingly work on them.

The recording age: tape, tracks and the producer

Every step in this story was a change in what could be captured. Microphones (1920s) let singers be intimate. Les Paul built multitrack overdubbing: his "Lover" (Capitol, 1948) was his first multitrack record, and in 1949 Bing Crosby gave him an Ampex tape recorder to which he added an extra playback head for sound-on-sound recording, where each overdub permanently replaced the previous mix. Tape could also be sped up or slowed down. For "In My Life" (Rubber Soul, 1965), George Martin recorded his piano solo on 22 October 1965 at half speed because he could not play it at tempo; played back at normal speed, it sounded twice as fast and an octave higher, with a harpsichord-like tone.

Producers and engineers became performers. In Kingston, Jamaica, King Tubby (Osbourne Ruddock, 1941-1989) started by taking the voices off instrumental "versions" on Duke Reid's mixing desk and found he could reshape what was left with fader moves, echo and reverb; his remixes became a genre called dub, and his 1974 "King Tubby Meets Rockers Uptown" is among the most celebrated dubs. In Detroit, bassist James Jamerson (1936-1983), a member of the uncredited Funk Brothers at Motown, played mostly with one finger, "the hook", on a 1962 Fender Precision Bass, and is credited with playing on the majority of the label's 1960s hits; counts of exactly how many are disputed. MIDI, introduced in 1983 (the specification was published in August 1983; the first demonstration, at the 1983 Winter NAMM show, connected a Prophet 600 and a Roland JP-6), lets instruments pass note information, never sound, to one another at 31,250 baud, and is the grammar of electronic production today.

In court: when does a song belong to someone?

Copyright protects a particular expression, not an idea, a style or a groove, and it treats the written composition and the recorded performance as separate things. The cases show where the lines have been drawn, and how contested they are.

• Sampling, 1991 and 2005. In Grand Upright Music v. Warner Bros. Records (S.D.N.Y., 17 December 1991), Judge Kevin Duffy held that Biz Markie's sampling of a Gilbert O'Sullivan recording without permission was infringement, opening with the line "Thou shalt not steal". Clearance costs rose and hip-hop producers shifted toward re-recording and paying the songwriters. In Bridgeport Music v. Dimension Films (Sixth Circuit, 3 June 2005), involving a two-second sample from Funkadelic, the court rejected a "too small to matter" defence for recordings: "Get a license or do not sample." Fair use remains available, and other courts have not all followed the rule.
• "Blurred Lines", 2015 and 2018. In Williams v. Gaye, a California jury found on 10 March 2015 that Pharrell Williams and Robin Thicke's song copied Marvin Gaye's "Got to Give It Up", and awarded about $7.4 million; the judge later cut it to about $5.3 million plus a share of future royalties. The Ninth Circuit affirmed in 2018 by 2-1, with Judge Jacqueline Nguyen dissenting that the songs differ in melody, harmony and rhythm and that the ruling risked protecting a style. The defence said the songs shared a feel; the Gaye side said specific elements were copied. It is among the most disputed copyright verdicts in recent music.
• "Stairway to Heaven", 2016 to 2020. The estate of Spirit's Randy California sued Led Zeppelin over the opening of "Stairway to Heaven" and Spirit's "Taurus". A jury found no infringement on 23 June 2016; a Ninth Circuit panel ordered a new trial in 2018; and on 9 March 2020 the full court, sitting en banc, ruled for Led Zeppelin and abolished the "inverse ratio rule" (the idea that strong evidence of access lowers the similarity needed). The US Supreme Court declined to hear the case on 5 October 2020. The claim turned on what was in the sheet-music deposit copy filed for the 1960s song, not the studio recording.

Two lessons recur. First, chord progressions and rhythms such as the twelve-bar form, the ii-V-I, the backbeat or the clave are common property; litigation is about specific melodic and structural combinations. Second, courts can reach different conclusions on similar-sounding facts, and musicians in the courtroom are not the same as musicians in the studio.

What a graduate just sees

• The twelve-bar blues is I-IV-V in three lines of four bars, with dominant sevenths and call-and-response words.
• Swing is a long-short ratio that shrinks as the tempo rises, not a fixed 2:1.
• ii-V-I works because the third and seventh of each chord barely move.
• A tritone substitute shares the V7's guide tones, swapped.
• The backbeat, the break, four on the floor and dembow are small grids of sixteen steps with a few hits each.
• On tape, pitch and speed are the same knob; digital tools separated them.
• Producers, engineers and bassists shaped the sound as much as the songs did.
• Copyright protects expression, not feel; courts differ on where the line lies.

Where it shows up next

• Composition, Arranging & Orchestration (35/72): voicing, texture and arranging for a horn section or band use the chords here.
• Music Technology & Production (35/73): compressors, samplers and loudness continue the studio story.
• Music Traditions of the World (35/69): the clave and bell patterns behind Afro-Cuban and Afrobeats grooves.
• In the world: session playing, mixing and mastering, songwriting, music supervision and publishing.

If you want to go deeper

• 📘 Textbook. Mark Levine, The Jazz Theory Book (Sher Music). The standard reference for chord-scale and ii-V-I thinking.
• 📘 Textbook. David Huber and Robert Runstein, Modern Recording Techniques (Routledge, later editions). The studio side of this piece.
• 📘 Gentler. Ted Gioia, The History of Jazz (Oxford University Press), and Mark Katz, Capturing Sound: How Technology Has Changed Music (University of California Press).
• 🌐 Free course. musictheory.net for chord drills, and the MIT subject 21M.296 Studies in Jazz and Popular Music (listed in MIT's catalogue; check MIT OpenCourseWare for materials).